Microscope fine adjustment mechanism



Aug. 7, 1951 J. R. ENFoRD l 2,553,702

` MICROSCOPE FINE ADJUSTMENT MECHANISM v muy,

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Filed Feb. '10, 19748 :inventor JAMES R` BENFORD atentecl ug. 7, 1951MICROSCOPE FINE ADJUSTMENT MECHANISM James R; Benford, lrondequoit, N.Y., assigner t Bausch & Lomb Optical Company, Rochester; N.- Y., acorporation of New York Application February 10, 1948, Serial No. 7,402

01; ss-w i 2 Claims.

This invention relates to microscopes and more particularly toimprovements in the fine adjustment mechanism for the optical systemthereof.

One of the objects of this invention is to provide a fine adjustmentmechanism which is relatively simple in structure yet eicient inoperation. A further object is to provide such a device which may bereadily and easily manufactured and adjusted with a minimum of labor andexpense. Still another object is to provide in a microscope a mechanismin which certain parts are used in common to effect both coarse and fineadjustments. These and other objects and advantages reside in certainnovel features of construction, arrangement and combination of parts aswill hereinafter be more fully described and pointed out in the appendedclaims.

Fig. 1 is a fragmentary view of a microscope stand, with parts insection, showing a preferred form of the invention,

Fig. 2 is an exploded view in perspective of certain details of theinvention, and

Fig. 3 is a fragmentary view partly in section of a second embodiment ofthis invention.

This invention is applied to a microscope, generally indicated at II) inFig. l of the drawing, having a base II, a support arm I2 suitably heldthereon and a specimen stage I3 and lens tube I4 secured to the supportarm I2 in substantial alignment with each other. The lens tube I4, whichsupports the optical system, is slidably mounted on slideways, notshown, for focusing said optical system. Although the preferred form ofthe invention shows the device applied to the movable lens tube I4, itmay equally well be used to accomplish fine focusing movements of anymovable member on the microscope such as the stage, the mechanicalstage, or a substage condenser.

According to this invention, movement of the lens tube I4 is produced bya coarse adjustment mechanism I5 and a fine adjustment mechanism I6having in common an operating shaft Il and a helical pinion I8 fixed tothe shaft and meshing with a mating inclined tooth rack I9 which isfixed to the lens tube. The operating shaft I'I is rotatably andslidably journaled in bushings 2l and 22 within the support arm I2 sothat the pinion I8 is traversable across the face of the rack I9. Knob23 is fixed to one end of shaft I'I so that the latter may be turned toeffect a coarse adjustment of lens tube I4 through the coaction of therack I9 and pinion I8.

The nne focusing adjustments of the lens tube I4 are accomplished bymoving the operating shaft I'I axially, without rotation, so as toutilize the camming action of the meshed inclined gear teeth on thehelical pinion I8 and rack I9 to move the tube I4. It is important thatsufficient clearance be provided between the ends of the pinion I8 andthe side walls of the pinion chamber 24 so that the pinion can be moveda total distance of substantially twice its length for best operatingeffect.

Actuating means of any desired form for moving the pinion is and shaftI'l axially may be provided such as an exteriorly threaded shaft head 25fixed in any suitable manner to the outer end of the shaft I'I andengaged with an interior thread 2B in a fine adjustment operating knob21. Since it is desirable to have the knob 27 turn freely and not moveaxially when the coarse adjustment mechanism I5 is in operation, acombination antifriction and antithrust bearing 28 is used as arotatable mounting means for the knob 2l. Bearing 28 is held in anydesired manner such as a friction t on the knob ZI and is concentricallynxed with respect to the shaft II on the support arm I2 by a retainingcollar 29 and screws 3l.

To facilitate operation of the ne adjustment mechanism, frictional dragmeans of any desired form may be provided to prevent rotation of shaftI'I due to the rotational component of force produced when an axialforce is applied to the shaft I'I. The frictional drag means here showncomprises an annular retarder member 32 having spring fingers 33 thereonand is attached to the shaft I "I, The spring lingers 33 contact theinner surface of a stationary annular member such as a brake drum 34 xedin any suitable manner such as by screws 35 to the support :arm I2 tocomplete the drag means. It is necessary that the rotational retardingforce produced by the frictional drag member be substantially in excessof the rotational force produced in the shaft I'I due to the reactionbetween the helical elements on pinion I8 of the rack I9 as the shaft Ilis moved axially.

Stop mechanism of any effective form may be provided for limiting theaxial travel of the shaft I'I. As here shown, a multi-turn stopmechanism connected between the operating knob 2l and the stationarysupport arm I2 accomplishes the limiting function. Said mechanismincludes the contiguous stop disks 3*, 3l, 38, and 33 carried loosely onthe shaft I'I and having limited rotational freedom therebetween.Rotational limitation may be effected in any desired manner such as theinterengaging drive lugs or abutments 4I, 42, 43, and 44 on the disks3G-39, respectively, which rotationally engage each other in an obviousmanner. In disk 36 is fixed an anchor pin 45 which enters acorresponding hole in the stationary arm I 2. A radial lug 43 on theperiphery of disk 39 slidably engages an interior slot 41 in the knob 2to connect the active end of the stop means to said knob.

In assembling this device, the stop disks 36-39 and bushing 22 are firstplaced in proper order on the fine adjustment end of the shaft I1 andthe threaded head 25 is then suitably fixed on the end of the shaft. Thecoarse adjustment end of the shaft isthen inserted from the right sideinto bushing 2I and subsequently bushing 22 is pressed into the supportarm I2 and .the anchor pin 45 is inserted into a hole in the arin` I2.The bearing 28 is now pressed on the end of the knob 21 and the outerdiameter of the bearing 28 is fitted within the retaining collar 29.wherein it is held by spinning over the o uter edge of the collar at48. The .two .Subfsemblies resulting from the aboveV operations .arethen asembled together by inserting the radial lug 4e in the interiorslot A'I'and turning the knob 2l until the shaft head 25 issufficiently-engaged within the interior thread 26 to allow theretaining collar -29 -to l-ieagainst the arm I2 where it is secured bythe screws 3|. Finally the brake drum -34 is slipped over the shaft I1and secured to the a-rm I2 by screws V35 and the knob 23 having thespring retarder member 32 fixed thereon is secured to the shaft.

In operating this embodiment of this invention, a'rota-tion force greatenough to overcome the static friction of the frictonal retarder member32 is applied by the operator to the coarse adjustment knob 23 to rotatethe pinion I8 in the usual manner to move the lens tube I4. Duringrotation-of the shaft I'I by coarse adjustment knob 23, the frictionbetween the head 25 and knob 21 causes the latter to rotate freelytogether with the head on its antifriction bearing 28. Rotation of thefine adjustment knob 2'! causes the head 25 to move along the interiorthread 25 since the shaft I'I is restrained from Arotating by theretarder member 32. Consequently, the shaft head 25 carries the helicalpinion I8 Vtransversely across the inclined tooth rack lI9 withoutrotating to move the lens tube I4 by the'camm-ing action of the inclinedteeth.

The'resulting rotational component of force imparted to Vthe shaft IIbythe inclined teeth is canceled by the braking force of the retardermember 32.

In the second embodiment of the invention illustrated in Fig. 3, theAoperating principle of the first embodiment is utilized in a simplifieddevice for moving an adjustably mounted member ofthe microscope such asa lens tube, stage, mechanical stage, or substage condenser. As hereshown, a helical pinion 50, meshed with an inclined tooth rack 5I onlens tube 5I', is ixedly mounted on a rotatable and axially mov.,- ableshaft 52 journaled in a -support arm 53 at 54 and 55 with a sliding t,The journal bearing 55 is formed in a'block 55 which is threaded intoarm 53 so as to facilitate assembly. A frictional retarder 55 of anydesired form for opposing motion of the shaft 52, as shown in Figure 3,may be provided. At the ends of the shaft 52, operating members such asknobs 51 and 58 are attached for turning the shaft. YFor a purpose tobe'described hereinafter, .the inner portions of knobs .51.and 58 areprovided .with the frusto-conical surfaces`59 and the portions of thearm adjacent the yknobs are also provided with the frusto-conicalsurfaces 60.

In operating .the modification shown in Fig. 3. the coarse adjustment`is effected in `the usual manner by turning the shaft 52 by :means ofknob A51er 58. In orderto produce fine :adjustments with this simplifiedform of the invention,

the tipsY of the .oper-ators-;thu1nbs` and forengers are placed in .the4V.sha/ped recesses formed Yby the respectively .adjacenttaperedsurfaces 59 and arm 53 the shaft 52 be mgved axially in the oppositedirection. Such Vaxial movements of the shaft 52 will cause the helicalpinion 5I! to exert a camming action on the rack 5I and thereby producerelatively minute movements of the lenstube 5l- ,In the above-.describeddisclosures, it will be seen that there are here provided simple andcompact coarse and nne adjustment mechanisms which interact smoothly andefficiently through a helical pinion and rackY connection to move anadjustable part of a microscope through very fine increments all inaccordance Withthe objects of this invention.

Although Vbut certain forms of'this invention have been shown anddescribed in detail, Ait-,will vbe understoodthatv still other forms arepossible and changes may be made in the arrangement of lparts andsubstitutionsmayY be made therein without departing from the spirit ofthe invention as `defined in the appended claims.

I claim:

l. In a microscope having a support carrying a lens memberand a stagemember and having at least one of said members movable relative to theother, the vcombination of a rack carried by the .movable member, ashaft mounted forrotational .and axial movementon the support, helicalgear meansv operatively connecting the shaft to the rack, means forrotating `the shaft to effect coarse adjustments of the `movable member,and means for` moving the shaft axially to effect ne adjustments of thev`nfivovable member, said Alast-named means comprising a head fixed onsaid shaft and a-rotatable, axiallyr'mmobilzed operating membercoaxially threaded to .said h ead so that rotation of the operatingmember causes the head and shaft -to travelaxially thereof.

2. In a microscope having a support carrying a vlens tube which isslidable thereon, the corn- ;bnationvof a vrack carried by the lenstube, a

. lshaft mounted for rotational and axialmovement on thesupport, ahelical pinion xed to the shaft and 'in operative engagement with therack, meansfor rotating the shaftto effect .coarse ad:- justment of thelens tube, a threaded head fixed to the shaft, an operating member whichlis rotatami' mounted 01.1 .the .Suppert and .held .against axialmovementsaid opretinemember and head @eine in threeded engagementwhereby rotation of the operating xrrlerrllvef-moves the Shaft axiallyto eect ne adjustment of the lens tube, aplurality of inter-.engageable-rstop members mounted on the ,shaft for operative engagement.With the ,operating member and Ithe support whereby the axial movementsof the shaft are limited.

JAMES n. BEN-FORD.

REFERENCES CITED YThe following references are of :record in the le. ofthis patent:

UNITED -sTArns PATENTS

